RESUMO
OBJECTIVE: Evaluate the accuracy of this bedside method to determine hemoglobin (Hb) concentration in general surgery over a wide range of Hb values and to determine potential sources of error. METHODS: Accuracy of Hb measurement using HemoCue (AB Leo Diagnostics, Helsinborg, Sweden) was assessed in 140 surgical blood samples using 7 HemoCue devices in comparison with a CO-Oximeter (IL 482, Instrumentation Laboratory, Lexington, MA). To analyze potential sources of error, packed red cells and fresh frozen plasma were reconstituted to randomized Hb levels of 2-18 g/dL. RESULTS: In the surgical blood samples, the Hb concentration determined by the CO-Oximeter (HbCOOX) ranged from 5.1 to 16.7 g/dL and the Hb concentration measured by HemoCue (HbHC) from 4.7 to 16.0 g/dL. Bias (HbCOOX - HbHC) between HbCOOX and HbHC was 0.6+/-0.6 g/dL (mean +/- SD) or 5.4+/-5.0% (p < 0.001). Also in the reconstituted blood, the bias between HbCOOX and HbHC was significant (0.2+/-0.3 g/dL or 2.1+/-3.2%; p < 0.001). The microcuvette explained 68% of the variability between HbCOOX and HbHC. HemoCue thus underestimates the Hb concentration by 2-5% and exhibits a 8-10 times higher variability with only 86.4% of HbHC being within +/- 10% of HbCOOX. CONCLUSION. Although the mean bias between HbCOOX and HbHC was relatively low, Hb measurement by HemoCue exhibited a significant variability. Loading multiple microcuvettes and averaging the results may increase the accuracy of Hb measurement by HemoCue.
